The present disclosure relates generally to the field of batteries and battery modules. More specifically, the present disclosure relates to battery cells that may be used in vehicular contexts, as well as other energy storage/expending applications.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
A vehicle that uses one or more battery systems for supporting propulsion, start stop, and/or regenerative braking functions can be referred to as an xEV, where the term “xEV” is defined herein to include all of the below described electrical vehicles, or any variations or combinations thereof.
A “start-stop vehicle” is defined as a vehicle that can disable the combustion engine when the vehicle is stopped and utilize a battery (energy storage) system to continue powering electrical consumers onboard the vehicle, including the entertainment system, navigation, lights, or other electronics, as well as to restart the engine when propulsion is desired. A lack of brake regeneration or electrical propulsion distinguishes a “start-stop vehicle” from other forms of xEVs.
As will be appreciated by those skilled in the art, hybrid electric vehicles (HEVs) combine an internal combustion engine (ICE) propulsion system and a battery-powered electric propulsion system, such as 48 volt, 130 volt, or 300 volt systems. The term HEV may include any variation of a hybrid electric vehicle, in which features such as brake regeneration, electrical propulsion, and stop-start are included.
A specific type of xEV is a micro-hybrid vehicle (Micro-HEV). Micro-HEV vehicles typically operate at low voltage, which is defined to be under 60V. Micro-HEV vehicles typically provide start stop, and distinguish themselves from “start-stop vehicles” through their use of brake regeneration. The brake regeneration power can typically range from 2 kW to 12 kW at peak, although other values can occur as well. A Micro-HEV vehicle can also provide some degree of electrical propulsion to the vehicle. If available, the amount of propulsion will not typically be sufficient to provide full motive force to the vehicle.
Full hybrid systems (FHEVs) and Mild hybrid systems (Mild-HEVs) may provide motive and other electrical power to the vehicle using one or more electric motors, using only an ICE, or using both. FHEVs are typically high-voltage (>60V), and are usually between 200V and 400V. Mild-HEVs typically operate between 60V and 200V. Depending on the size of the vehicle, a Mild-HEV can provide between 10-20 kW of brake regeneration or propulsion, while a FHEV provides 15-100 kW. The Mild-HEV system may also apply some level of power assist, during acceleration for example, to supplement the ICE, while the FHEV can often use the electrical motor as the sole source of propulsion for short periods, and in general uses the electrical motor as a more significant source of propulsion than does a Mild-HEV.
In addition, a plug-in electric vehicle (PEV) is any vehicle that can be charged from an external source of electricity, such as wall sockets, and the energy stored in the rechargeable battery packs drives or contributes to drive the wheels. PEVs are a subcategory of xEV that include all-electric or battery electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicle conversions of hybrid electric vehicles and conventional ICE vehicles. BEVs are driven entirely by electric power and lack an internal combustion engine. PHEVs have an internal combustion engine and a source of electric motive power, with the electric motive power capable of providing all or nearly all of the vehicle's propulsion needs. PHEVs can utilize one or more of a pure electric mode (“EV mode”), a pure internal combustion mode, and a hybrid mode.
xEVs as described above may provide a number of advantages as compared to more traditional gas-powered vehicles using only ICEs and traditional electrical systems, which are typically 12 volt systems powered by a lead acid battery. For example, xEVs may produce fewer undesirable emission products and may exhibit greater fuel efficiency as compared to traditional vehicles and, in some cases, such xEVs may eliminate the use of gasoline entirely, as is the case of certain types of BEVs.
As xEV technology continues to evolve, there is a need to provide improved power sources (e.g., battery systems or modules) for such vehicles. For example, it is desirable to increase the distance that such vehicles may travel without the need to recharge the batteries. Additionally, it may also be desirable to improve the performance of such batteries and to reduce the cost associated with the battery systems.
Conventional xEVs have been found to be functionally limited by their electric energy systems that supply power to their electric motor/generator and vehicle accessories. Typically, an electric motor is powered by an energy source that needs to store energy suitable for high-power discharges as well as for electric demands generated by various driving conditions.
In conventional electrical energy delivery systems for vehicles, e.g., xEVs, a plural sources of electrical energy can interfere with one another. Interference between these electrical energy sources can take the form of a conflict for control of the voltage of the power network, or a lack of synchronization with respect to handing off control of the voltage of the power network.
In any vehicle, one or more power networks (i.e., powernets) exist to allow supply and demand of electrical energy to meet. It is important that the powernet is operated in a stable manner, usually requiring the voltage to operate in a defined window. In a traditional non-hybridized ICE vehicle, two devices are capable of maintaining voltage on the powernet: the alternator (if it is on), or the battery. In this simple example, the battery is a passive device and can operate at the alternator output voltage or control the voltage via its own operation. In this way, the voltage on the powernet is naturally maintained.
In many representations of HEV, MHEV, or other vehicles, two or more electrical devices on the vehicle may be capable of providing, receiving, or transforming electrical energy. These devices may be batteries, capacitors, alternators, motors, generators, voltage/current/power regulation devices, such as inverters and DC/DC converters, or other devices. In some cases, there may exist more than one electrical device capable of actively controlling the powernet voltage or current. As a subset of those cases, it is also possible that all electrical devices are capable of controlling the powernet voltage or current.
At any time, only one “primary” device can control the powernet voltage or current; other “secondary” devices must recognize the control of the “primary” device. If this fails to occur, then either no device controls powernet voltage or current, or two or more devices conflict in their attempts to do so. Further, transfer of voltage or current control must be managed among devices capable of providing control such that the controlling device is itself stable and is providing/receiving/transforming sufficient current to maintain powernet stability. Failure to do so for even a brief time can cause interruption to critical vehicle functions.
Thus, there exists a need for a system and method configured to mitigate these control issues within a power network(s) of a vehicle.